Draft Waterway Characteristics for Riverine Encounters

The following is my first attempt at a simple D6 based scale for potential encounters on a river. The scales give the "chances" of a particular occurrence, either a Hazard or an Encounter - the remaining "chances" are by default a result of No Encounter. 

So let's start with some definitions I think:

A waterway is any navigable body of water. Broad distinctions are useful to avoid ambiguity, and disambiguation will be of varying importance depending on the nuance of the equivalent word in other languages. 

A first distinction is necessary between maritime shipping routes and waterways used by inland water craft. Maritime shipping routes cross oceans and seas, and some lakes, where navigability is assumed, and no engineering is required, except to provide the draft for deep-sea shipping to approach seaports (channels), or to provide a short cut across an isthmus; this is the function of ship canals. Dredged channels in the sea are not usually described as waterways.

So when we're talking about "riverine" encounters, we're really talking about waterways except when we're referring to those smaller rivers with significant cascades and rapids that can only be traversed by small canoes and portage (hauling the canoe overland around the water hazard). These are a special case and might actually be better treated using encounters based on the surrounding terrain with hazards as set encounters or via a pointcrawl, but it's nearly always the exception that proves the rule.

In terms of Hazard (Danger), a stretch of waterway can either be:

• Extreme - 4 in 6 chance of Hazard (only Desolate)
• Treacherous - 3 in 6 chance of Hazard (cannot be Populated or Congested)
• Hazardous - 2 in 6 chance of Hazard (cannot be Populated or Congested)
• Choked - 2 in 6 chance of Hazard (only Congested)
• Unimproved - 1 in 6 chance of Hazard
• Ruined - 1 in 6 chance of Hazard 
• Improved - 0 in 6 chance of Hazard (set-piece Hazards only, eg. canal)

From an Encounters perspective (Population), a stretch of waterway can be:

• Floating City - 4 in 6 chance of Encounter (only Improved)
• Congested - 3 in 6 chance of Encounter (cannot be Treacherous or Hazardous)
• Populated - 2 in 6 chance of Encounter (cannot be Treacherous or Hazardous)
• Remote - 1 in 6 chance of Encounter
• Wild - 1 in 6 chance of Encounter (animals only)
• Desolate - 0 in 6 chance of Encounter (set-piece Encounters only)

Optional: at night, the Population drops one level unless "Wild" or "Desolate" already. "Remote" instead changes to "Wild" to reflect the lack of human encounters during the darker hours.

To create a more uneventful journey, substitute D8 or D10, but leave the scaled "chances" the same.